1. Field of the Invention
The present invention relates to a motor, and an apparatus and method for controlling a driving of a linear motor mounted in a linear compressor.
2. Description of the Related Art
Generally, a linear compressor, especially, a linear motor arranged in a linear compressor is not provided with a crankshaft which converts a rotational movement into a linear movement and thus has reduced frictional loss. According to this, a compression efficiency of the linear compressor is better than that of a general compressor.
When the linear motor compressor is used in a refrigerator or an air conditioner, a stroke voltage input into the linear motor is varied to thus vary a compression ratio of the linear compressor, thereby controlling a freezing or cooling capacity.
The linear compressor will be explained with reference to FIG. 1.
FIG. 1 is a sectional view showing a linear compressor in accordance with the conventional art.
As shown in FIG. 1, the conventional linear compressor comprises: a casing 2 having a gas suction pipe 5 and a gas discharge pipe 1 installed therein. A frame unit 6 is installed in the casing 2 and a linear motor 100 is fixed to the frame unit 6 for a linear movement. A compression unit 7 is coupled to a movable element 100-3 of the linear motor 100 and is supported at the frame unit 6 and a resonance spring unit 4 is provided for elastically supporting the movable element 100-3 of the linear motor 100 for movement in a linear movement direction and thus inducing a resonance movement. Herein, the linear motor is composed of the movable element 100-3, an outer stator 100-1, and an inner stator 100-2.
The linear motor 100 installed in the linear compressor is composed of a coil having a plurality of windings. The linear motor 100 will be explained with reference to FIG. 2.
FIG. 2 shows an equivalence circuit of the motor arranged in the linear compressor in accordance with the conventional art.
As shown in FIG. 2, the equivalence circuit of the linear motor 100 is composed of one coil L having the predetermined number of winding and a resistor R. That is, the number of winding of the linear motor coil L is designed to correspond to a normal load.
However, in the linear compressor according to the conventional art, the number of winding of the linear motor coil is designed in advance so as to correspond to the normal load and a triac (not shown) which controls an alternating current power supplied to the linear motor when the motor is driven with a normal mode generates harmonics loss, thereby lowering a compressor efficiency.
That is, the conventional linear motor can not vary the number of winding of the inner coil, so that efficiency of the compressor is lowered by the harmonics loss.
Also, the linear motor mounted in the conventional linear compressor and having one coil stops when it is overloaded. That is, when the overload is generated at the linear motor, electric current for driving the linear motor can not be increased.